Exhaust manifold



May 7, 1935 c. w. sTEwARD 2;O0,72Y2

EXHAUST MANIFOLD Filedy Jan. 6, 1933 |N\ENTOR Coun w.51-ewm2v,

BY HIS ATTORNEY Patentedl May 7, 1935 I,

UNITED STATES PATENT oFFici.l

ExnAUs'r .mim-fom Colby W. Steward, Kenmore, N. Y., assignor to CurtissAeroplane MotorCompany, Inc., a

corporation of New York Application January s; 1933, sei-isis. 50,461

s claims. ((01 so-a9) This invention relates to multi-cylinder internalcombustion engines, and more particul, larly to improvements in exhaustmanifolds for such engines.

, 5 In high performance aircraft engines, particularly those engines inwhich the cylinders are in line, it has been customary in the past to`provide the exhaust port of each cylinder with anindividual shorttubular exhaust stack. Such 10. stacks' are awkward in appearance, andsince they necessarily protrude from the engine body into the.slipstream of the aircraft, they cause an yunnecessary degree of drag,which has a' tendency to impede the speed of the aircraft.

1li'A These stacks assist in accentuating the sharpr 25 inheavier-than-air craft, and usually impose an exhaust back pressure onthe high perform-r ance engine which causes loss of. power and possibleoverheating of the valves.

My invention provides a^simple, light ex-y haust manifold for engines ofthe type mentioned, having the following objects: A (a) To allow freeypassage of the exhaust gas to the outside air, without restriction;

-(b) To provide an exhaust manifold which 35,y may be readilystreamlined, minimizing parasitic drag;

(c) To provide. a unitary manifold `which may.

vbe readily attached and detached;

(d) To provide a manifold which has the ef`- fect of-'moderating thesharp exhaust reports' of the individual cylinders; l (e) To provide amanifold which may be fabricated from a light metal casting, such asaluminung` y (f) To provide a cast aluminum exhaust man-'- iiold whichis not likely to burn or melt; (y), To provide a manifold which willprevent Jan inrush of cold air, which might cause such damage as warpingtoUthe hot valves of the en` gine. f

Further objects of the invention will be apparent from a considerationof the drawing, from the followingv description, and from .the claims.For a clearer understanding of the invention, reference may be made tothe drawing,'in which similar numbers designate similar parts, and inwhich:

Fig. l is a: perspective view of the manifold as y applied to one bankof a V type multi-cylinder engine I 5 Fig. 2 is a perspectiveview of aportion of Fig. l, partly in section to show the interior construction;Y

' Fig. 3 is a plan, partly broken away, of a portion of the manifold;A,and/ 10 Figs. i, 5 and.6 are sections on the lines 4 6," 5 5 and 6 6,respectively, of Fig. 3.

In the drawing, a conventional engine cylinder head III is provided witha flat face II 'to lwhich any exhaust pipes or maniifoldsmayl be l5attached. Exhaust ports, not' shown, are formed in the cylinder head I0and are open to the outsidel at theface II.

The manifold of the invention is provided Iwith aflange I2 adapted tolie adjacent the face II, 20VA andV to be attached thereto by suitablebolts'f and nuts, to be inserted through openings I3 formed inthe ange.Extending out from said flange are,- a plurality of short stacks I4, thehollow of each stack extending through the flange 25 I2 to register4with an engine exhaust port.

4Along the outer ends of the row ofstacks'll, la. rsubstantiallyU-shaped cylindrical member I! is attached,the outer endsof the stacksI4 com-Y municating with the hollow of the member I5 by 30 Vopenings I6formed in the inner portion thereof. The upper and lower side plates I1and I 8, respectively, extend outwardly, away from the cylinders,.,a'ndtaper toward each other, so that the outeredges of the plates are spaceda dis- 35 tance c apart, said distance being somewhat less than theinside diameter d rof the stacks I4. l A longitudinal opening I9 istherebyformed at the y open edges of the plates I1 and I8, of theUmember I5, said opening allowing` for the free exit 40 of exhaustgases,issuing from the several exhaust stacks I4. .The chamber 20 whichis the hollow `of the member I5 acts as a diffusion chamber for theexhaust gases issuing from the stacks ,|4, before said gases pass to theoutside air 45 through the attenuated opening I9, lessening the Y sharpreport of such exhaust gases.

To further strengthen the plates I'lfand I8. to provide guides which.lead'the gases outward, and to provide bailles which tend to' preventany in- 50 ward rush of air to the manifold, a plurality of partitions2I are provided -between the outer edges of the plates I1 and I8,extending inwardly to denne vthe outer boundary of the chamber 2li.These partitions are longitudinally spaced by a u distance' e,saiddistance being substantially the same as the distance betweencenters of the several stacks I4.

By the location of each partition 2| opposite the space between adjacentstacks I4, a rectangular outlet opening is formed, bounded by successivepartitions 2| and by the upper and lower plates I'I and I8, throughwhich the main blast of exhaust gas issuing from the opposite stack I4may pass. The area of such opening is equal to, or greater than, thecross sectional area of any of the stacks I4, and so causes norestriction of out-flowing gas. The chamber 20, however,al lows part ofsuch gas to dissipate and pass out through the other rectangularopenings formed as part of the main opening I9, allowing for moderationof exhaust noise and for the distribution of heat.

The purpose of the chamber 20 is to allow for a slight interflow ofgases from the various exhaust stacks before they mingle with theoutside air, and to eliminate a hot spot, at a location where normaltubular exhaust stacks become extremely hot. In actual practice, commonexhaust stacks become hottest at a distance removed from the cylinderport, the distance being about one 'exhaust port diameter removed fromthe port. With this effect in mind, the continuous chamber 20 is madejust at this location to allow for additional expansion space for thehot gases at this point and to hold the manifold at a substantiallyuniform temperature. This chamber is made cylindricalin order toeliminate flat surfaces to prevent pulsation or panting of the material,which occurs in flat surfaces. Likewise, the tubular exhaust stacks I4between the engine exhaust ports and the chamber 20 are so made toeliminate at surfaces to avoid pulsation or panting. It has been foundin the past that,

regardless'of the material from which Ystacks may be made, if they arenot given a curved con- Lformation the at material will pulsate-underthe repetitive exhaust impulses, e'ventuallyfracturing the material. Inmany instances, sections of flat exhaust manifold plates have actual lyblown out regardless of the material from which they may be made. Afterthe gases have had a slight opportunity to expand in the regionA of thechamber 20, and after they receive a slight admixture of cool airtherefrom, the cooler gases may pass from the rectangular ducts I9 tothe atmosphere. It should be appreciated that all of the cylinders donot exhaust at once into this manifoldthey exhaust in more or lessconsecuf tive order, so that the gases issuing from any one exhaust portat any instant will tend to pass through the directly opposite outletport I9. The draft caused by the passage of the gases through thechamber 20 will tend to suck cooler air from adjacent ports I9 throughthe chamber 20 to keep this ordinarily hottest part of the structure,

cool. i r

The tubular stacks I4`are also a convenient form for manufacture andstill more important, they provide external accessibility to the studswhich hold the manifold to the cylinder block at the openings I3. Theutility of the shape of the ducts I9 accrues from the straight lineconformation of the manifold as a whole. I t will be appreciated thatthe normal engine installations in the past have utilized straightcircular exhaust stacks projecting from the cowling surrounding theengine. The line of stacks thus formed offers an unnecessry degree ofdrag in the airthey protrude from the engine cowling in a slightlycurved line which is not parallel to the airstream flowing thereover. Byproviding the unitary manifold of this invention, the series of outletsare aligned in a straight line parallel to the airstream flowingthereover, and thereby, offer less parasitic drag.

The manifold above described could readily be fabricated from sheetmetal, welded or riveted to the proper form, but the preferredembodiment, as shown, combines the various elements in a single unitarycasting. The casting may be made from aluminum, or from suitable castingalloys of that metal, giving the advantage of lightness, rigidity, andlow cost. As a casting, it would be desirable to form stiffening webs 22across the plates I'I and I8, and to form webs 23 between adjacentstacks I4.

When used with V-type aircraft engines, the stacks I4 would tend topoint outwardly and downwardly, so the U member I5 may be formed tochange the direction of the gases, ejecting them horizontally orupwardly. The formation of the manifold may readily be changed, withoutdeparting from the scope of the invention, to adapt it to engines ofdifferent form, and to accommodate it to cowling or body structuresurrounding the engine.

While I have described my invention in detail in its present preferredembodiment, it will be obvious to those skilled in the art, afterunderstanding my invention, that various changes and modifications maybe made therein without departing from the spirit or scope thereof. Iaim in the appended claims to cover all such modifications and changes.

Whatis claimed is: Y

1. A unit exhaust manifold for a multi-cylinder engine comprising anupper longitudinal plate, a lower longitudinal plate, a plurality ofmeans for joining said plates between the successive engine cylinderexhaust ports, said means being adapted for attachment to saidcylinders, and a plurality of partitions for joining the outer edges ofsaid plates, whereby outlet openings are formed by the juxtaposition ofsaid plates and of said partitions, and whereby a longitudinal passageis formed by the boundaries established by said upper and lower plates,said means, and the inner edges of said partitions.

2. An exhaust manifold for a multi-cylinder internal combustion enginecomprising a unit cored casting, said casting having openings inregister with the exhaust ports of the individual cylinders, havingformed therein a passage bridging and registering with said openings,and having formed therein a plurality of openings communicating withsaid passage and with the outside air.

3. An exhaust manifold for a multi-cylinder internal combustion enginecomprising a unit cored casting, said casting having openings toregister with thelexhaust ports of the individual cylinders, havingformed therein a passage bridging and registering with said openings,and having formed therein a plurality of openings communicating withsaid passage and with the outside air, -said last mentioned openingsbeing substantially opposite said rst mentioned openings.

4. An exhaust manifold for a multi-cylinder internal combustion enginehaving exhaust ports for the individual cylinders arranged insubstantially a straight line, comprising a unit cored casting having acommon passage into which the craft and by the varied length of thestacks, exhaust gases are led, said casting having formed 75 therein aplurality of substantially shaped outlet openings arranged in a linesubstantially parallel to said cylinder ports. 5. An` exhaust manifoldfor a multi-cylinder' internal combustion engine having exhaust portsfor each cylinder, including a substantially cylindrical chamber intowhich the exhaust gases from the cylinders are adapted to pass, saidchamber having a narrowopening along a side thereof for the escape ofgases therefrom, and a plurality of spaced inwardly extending partitionscarried by said chamber adjacent the edges of said opening.

8. An exhaust manifold for a multi-cylinder internal combustion engineincluding a plurality of stacks attached to said cylinders. said stacksbeing adapted to register with the exhaust ports of the severalcylinders, a substantially cylindrical chamber bridging the outer endsof said stacks and into which said gases may pass and mingle. and saidchamber having formed therein a narrow outlet opening substantiallycoexiensive with the length thereof.

"l. An exhaust manifold for a multi-cylinder internal combustion engineincluding a plurality of stacks attached to said cylinders, said stacksbeingadaptedtoregisterwiththeexhaustports of the several cylinderaasubstantially cylindrical chamber bridging the outer ends of said stacksand into which said gases may pass and mingle, said chamber havingformedtherein a narrow outlet opening substantially coextensiverwith'V thelength thereof, and inwardly extending partitions carried by andbridging the edges of said opening, said partitions being adapted toreinforce saidedgesfromspreadingandtominimiaean inrush of external-airto said chamber.

8. In combination with an in-line multi-cylinderr engine having circularexhaust ports adjacent the upper cylinder ends, a unit exhaust manifoldinto which the exhaust gases from said cylinders may pass, said manifoldhaving an outlet opening substantially coextensive with the length ofsaid engine, the width of said opening being less than the diameter ofany said exhaust ports, but the outlet area thereof being substantiallyequaltoor greaterthanthecombinedareaof said exhaust ports.

OOLBY W. STEWARD.

